1. Field of the Invention
The invention relates in general to a noise suppressing method for switching on/off a flat panel display, and more particularly, to a noise suppressing method that outputs a black burst signal from a driver IC at the switch-on transient, and outputs a charge reset signal from the driving chip at the switch-off transient.
2. Description of the Related Art
The fast development of multimedia is benefited by the progress of improvement in semiconductor devices or display apparatus. Having excellent display quality and being economic, the cathode ray tube has occupied the dominant position in the display market for years. However, problems involved with space utilization and power consumption remain unresolved for cathode ray tubes. The demands for being light, thin, short and small as well as low power consumption cannot be met with cathode ray tubes. Therefore, the thin-film transistor liquid crystal display (TFT-LCD) with high quality, effective space utilization, low power consumption, and non-radiation has gradually come to dominate the market and become main stream for display apparatus.
Currently, frame noise is caused by the unstable signal generated by switching on/off the flat panel display. The frame noise caused at the transient for switching on the flat panel display is generated by the unstable signal source. The frame noise caused at the transient for switching off the flat panel display is generated because signal termination process is not performed when the signal source is terminated, while the flat panel display is switched with the latest displayed frame. For example, in the thin-film transistor liquid crystal display, transient brightness appears on the displayed frame at the switch-on transient. In addition, if only the signal and the power source of the signal are switched off without switching off the backlight source at the switch-off transient, the image of the display frame is faded with a very slow speed. On the other hand, if the backlight source is switched off simultaneously with the signal and the power source of the signal, tidal variation of shadow appears in the display. Such phenomenon is referred as fade-out.
The conventional technique to resolve the fade-out phenomenon includes switching on all the pixels to make uniform the charges in each of the pixels. In this technique, all the pixels are switched on by the gate driver IC or row driver IC at the switch-off transient, so that the pixels can be quickly and uniformly discharged. However, when all the pixels are switched on by the gate driver chip to achieve the objective of making uniform the charges of the pixels controlled by the same data line, the charges of the pixels are made uniform along the whole display line in the vertical direction (that is, the display line controlled by the same data line).
In addition, at the switch-off transient, a large signal current has to be provided by the gate driver chip to switch on all the pixels. This is very likely to cause the concern of related circuit quality. In the example of a display with the resolution of 1024×768, the current of 1 mA has to be provided for switching on the thin-film transistor controlled by one scan line. By switching on the thin-film transistors controlled by 768 data lines at the same time, the required total current of 768 mA is very likely to damage the related circuit. Further, when the above charge uniformization is applied to a larger display panel with a higher resolution, the current for switching on all the pixels is further increased in accordance with the resolution. Therefore, the prior art technique for making uniform the charges of all the pixels to suppress the noise caused at the switch-off transient cannot be effectively applied to large panel.